Servomotor controller

Abstract

When contents of a program for machining to be executed by a servomotor indicate a cutting mode, a current command is generated by performing speed loop processing by using a speed loop gain for cutting mode, and moreover, a voltage command to a servo amplifier is generated by performing proportional-plus-integral (PI) current loop processing in accordance with the generated current command. On the other hand, when the contents of the machining program indicate a positioning mode, a current command is generated by performing speed loop processing by using a speed loop gain for positioning mode, and moreover, a voltage command to the servo amplifier is generated by performing integral-plus-proportional (I-P) current loop processing in accordance with the generated current command.

What is claimed is:  
     
       1. A servomotor controller comprising: 
       an operation mode judging unit judging whether the contents of a command indicate a cutting mode or a positioning mode; and  
       a speed loop gain storing unit storing a speed loop gain for cutting mode and a speed loop gain for positioning mode,  
       wherein control is performed by selecting either of the speed loop gain for cutting more or the loop gain for positioning mode stored in said speed loop gain storing unit in accordance with a judgment result of said operation mode judging unit.  
     
     
       2. A servomotor controller according to claim  1 , further comprising a current loop gain storing unit storing a current loop gain for cutting mode and a current loop gain for positioning mode, wherein control is performed by selecting either of the current loop gain for cutting mode or the current loop gain for positioning mode stored in said current loop gain storing unit in accordance with a judgment result of said operating mode judging unit. 
     
     
       3. A servomotor controller according to claim  1 , further comprising a first current control configuration for performing proportional-plus-integral type current loop processing in accordance with a current command generated through speed loop processing and a feedback current fed back from a servo amplifier, and a second current control configuration for performing integral-plus-proportional type current loop processing in accordance with a current command generated through speed loop processing and a feedback current fed back from the servo amplifier, wherein switching from or to the first current control configuration to or from the second current control configuration is performed in accordance with a judgment result of said operation mode judging unit. 
     
     
       4. A servomotor controller according to claim  1  wherein, when said operation mode judging unit judges that contents of a command indicate a cutting mode, said speed loop gain changing means performs changeover of a speed loop gain to the speed loop gain for cutting mode, and also said current loop gain changing unit performs changeover of a current loop gain to the current loop gain for cutting mode, and further said current loop configuration performs changeover so that proportional-plus-integral type current loop processing is carried out, while, when said operation mode judging unit judges that contents of a command indicate a positioning mode, said speed loop gain changing unit performs changeover of a speed loop gain to the speed loop gain for positioning mode, and also said current loop gain changing means performs changeover of a current loop gain to the current loop gain for positioning mode, and further said current loop configuration performs changeover so that integral-plus-proportional type current loop processing is carried out. 
     
     
       5. An apparatus comprising: 
       an operation mode judging unit judging whether contents of a command indicate a cutting mode or a positioning mode of a servomotor driven by a servo amplifier; and  
       a voltage command generator outputting a voltage command to the servo amplifier, wherein  
       if the command is judged to be a cutting mode, then the voltage command is generated by performing proportional plus integral current loop processing,  
       if the command is judged to be a positioning mode, then the voltage command is generated by performing integral plus proportional current loop processing.  
     
     
       6. A method of controlling a servomotor driven by a servo amplifier, comprising: 
       judging whether a command to the servomotor indicates a cutting mode or a positioning mode;  
       if the judged command is cutting, then outputting a voltage command to the servo amplifier by performing proportional plus integral current loop processing,  
       if the judged command is positioning, then outputting a voltage command to the servo amplifier by performing integral plus proportional current loop processing.